Epilepsy Testing

There are many usual methods of epilepsy testing, such as Wada testing, EEG, EMU and MRI. One or more of these may be needed for proper diagnosis. Routine EEG has its limitations. The short recording time means clinical seizures are rarely captured. Activity outside of seizures are also typically absent on the brief recording. Video EEG (VEEG) or long-term video-EEG monitoring (LTM) is often used for the purpose of looking at where in the brain seizures happen. This is called finding the epileptogenic zone.

Phase I monitoring is the first step for deciding whether someone is a candidate for epilepsy surgery. This step involves admission to the Seton Epilepsy Monitoring Unit (EMU). The typical admission time for a Phase I evaluation is four or five days. You can find more information about the testing procedures used during Phase I monitoring below, or download our PDF on what to expect during a stay in the EMU.

Neuropsychological Evaluation

Epilepsy can affect people in many ways, depending on where seizures happen in the brain and their cause. In particular, cognitive abilities such as memory, attention and reasoning are often affected. The purpose of this examination is to measure these abilities to determine how recurrent seizures have affected an individual.

  • This information can be very helpful in looking at potential treatment options for certain types of epilepsy, especially surgery.
  • Information gained from this evaluation sometimes helps with finding the point of origin for seizures.
  • Results also serve as a baseline for measuring change in mental abilities with treatment.
  • The information can be instrumental in helping individuals better adjust to the effects of epilepsy in everyday settings like work or school.

The evaluation starts with an initial interview (about 60 minutes) followed by standardized testing of mental abilities (four to six hours). During this time, several abilities are assessed:

  • Memory
  • Attention
  • Motor skills
  • Sensory perceptions (like touch, vision or hearing)
  • Language processes
  • Intellectual abilities
  • Complex problem-solving and reasoning
  • Personality factors

The evaluation is non-invasive and uses either a paper and pencil or is taken on a computer. A follow-up meeting (about 60 minutes) to review results is scheduled on a separate day.

For the test day, it is important to bring prescription eyeglasses and hearing aids if they are needed. You also need to bring a complete list of current medications and the dosage for each one. If you have done this type of testing in the past, please bring a copy of the results if available. Otherwise, the only preparation for the exam day is to have a good night’s sleep, eat a good breakfast and bring a snack if needed. A lunch break will be provided during the test day. Comfortable clothes are also recommended.

Neuropsychological exams can be scheduled through a physician referral. The cost is typically covered, either in part or in total, by most insurance companies. If you have questions about coverage, please call your insurance provider. You can also call the Seton billing office at 512-324-3540.

Neuroimaging Studies

MRI

An MRI (magnetic resonance imaging) of the brain can help find any anatomical abnormalities that may be causing seizures. These include brain tumors, defects or previous damage from an earlier trauma or infection. The area of the brain where seizures start from can also be located with an MRI.

PET

A positron emission tomography (PET) scan is used to find out which part of the brain has lower metabolism than other parts. A seizure focus usually has a lower metabolism compared to the surrounding normal brain. A PET scan is performed by injecting a small amount of radioactive tracer and then looking at how much of it is metabolized by different parts of the brain. A PET scan is usually performed on a person with epilepsy whose MRI did not show any clear issues.

MEG

A magnetoencephalography (MEG) study measures very small magnetic field changes in the brain. This helps to locate seizure focus, usually in people who had a normal MRI of the brain.

Ictal SPECT

The ictal SPECT (single-photon emission computed tomography) study shows blood supply in the brain during a seizure. The results are then compared to SPECT images taken while the individual was not seizing. Together, these two images show the area in the brain where there is increased blood flow during a seizure.

EEG

The electroencephalogram (EEG) records electrical activity from the surface of the brain. This is converted to a digital signal and displayed on a monitor. A specially trained neurologist can analyze and interpret the data. An EEG records the normal state of the brain. Abnormalities that are associated with seizures can also be shown.

Trained technicians perform EEGs at our Austin based hospital epilepsy center and clinics. They measure each person’s head to choose the best positioning of the electrodes to cover the brain activity. Additional electrodes are placed to monitor heart activity and eye movements. This helps separate inaccurate data from true brain activity. Sometimes sleep deprivation or other activating procedures are used to bring out abnormalities in the EEG. Linking these with seizures can mean a better diagnosis.

There are several types of EEGs, which vary based on the length of the recording or the type of electrodes used:

  • The most common EEG is a routine study. Routine EEGs are done in the office, lab or hospital and last 40 to 60 minutes.
  • Ambulatory EEGs are longer recordings that last anywhere from 24 to 72 hours. During this time, the person being tested is connected to a small recorder that he or she can take home. The individual then records any seizures or events in a log book.
  • Inpatient video EEG (VEEG) is a longer type of EEG that records both video and sound, and is evaluated in combination with computerized EEG patterns.
  • Continuous video EEG, or prolonged EEG, is available at University Medical Center Brackenridge location, and can be useful for longer recording periods.
  • An intracranial EEG places electrodes directly on the brain’s surface for more in-depth recordings.

Our team of trained epileptologists read the majority of the routine EEGs as well as all other types of EEGs performed at our center.

Wada Examination

The purpose of the Wada exam (also known as the intracarotid amobarbital test) is to better determine which parts of the brain actively contribute to language and memory functions. The Wada test is named after Juhn Wada, the developer of the procedure. This exam involves multiple members of the epilepsy team, including a neuroradiologist, neurologist and a neuropsychologist. Most people who are being considered for epilepsy surgery undergo the Wada test to help with surgical planning.

The Wada test begins by placing a small catheter in the arteries of the neck that supply blood to the brain. Through this catheter, a sedative medication (barbiturate) is injected into the arteries and puts approximately 2/3 of one side of the brain to sleep. The medication is fast-acting and wears off within a few minutes. While part of the brain is asleep, the rest of the brain is tested for its ability to comprehend and produce language. The tested portion of the brain is also checked for its ability to learn and recall new information.

Once one side of the brain has been tested and the medication has fully worn off, the catheter is then moved to an artery supplying the other side of the brain. Next, that side of the brain is tested the same way.

A few days prior to the Wada test, the individual will meet with the neuropsychologist at University Medical Center Brackenridge epilepsy center to review the procedure and practice all tasks used in the exam. Participants are welcome to ask questions at this time.

On the day of the exam, patients report to the Brackenridge Hospital radiology department. Shortly after arrival, the EEG technician attaches electrodes to the scalp for continuous monitoring throughout the exam. Individuals then meet with the neuroradiologist, who will provide more information about the test, as well as offer an opportunity to ask further questions.

Next, they move to the radiology suite and a small incision is made in the thigh for insertion of the catheter. The catheter is inserted and extended until it reaches the carotid arteries in the neck. Once the catheter is in place, the neuroradiologist completes an angiogram, which injects dye through the catheter. As the dye flows through the blood vessels, a special X-ray machine takes pictures of the brain’s blood vessels. While the catheter is still in place, a neuropsychologist injects the sedative and then tests language and memory.

At the end of the test, participants return to the neuroradiology holding room where they rest for a few hours. This gives the incision site time to fully clot before trying to walk. The procedure is completed in one day and patients can go home in the afternoon.

To prepare, it is important that you do not eat or drink after midnight the day prior to the procedure. However, it is necessary to keep taking regularly scheduled medications, and it’s fine to drink enough water to do so. If you wear prescription eyeglasses or hearing aids, it is necessary to bring them as well.